DACs: Airport Express vs waveterminal vs mini-dac


I know this is impossible to quantify, but with a good stereo system (Cayin TA30 tube integrated amp & Green Mountain Audio Europa speakers), what's the magnitude of difference using the following dacs?

Airport Express (I already have the AX, and can connect it to the integrated amp with RCA's [analog])

Waveterminal U24: computer to USB to waveterminal to amp (waveterminal does the DA conversion)

Inexpensive DAC like ART DIO with waveterminal: computer to USB to waveterminal to ART DIO to amp (ART DIO does DA conversion)

Apogee mini-dac: computer to USB to mini-dac to amp

Other?

What's the best bang for the buck?
mschamberlin3865
Thanks for the information Edumke! What adds so much to it is that you said that initially you liked the Transit. I recently plugged my headphone amp and AOS Piccolo DAC into a Nakamichi CD player (although 10 years old), and noticed the same thing. The Transit was good, but when I heard the standalone CD player, the laptop setup seemed to be missing a natural and musical sense of space. Not a huge difference but definitely a difference. This is what has inspired me to see if I can upgrade the system. My amp, cans are good, and the Piccolo DAC is source dependant and a great little unit for the money. It seemed that the Transit was the weak link.

I would greatly appreciate it if you could setup your waveterminal when you get back. I really think I am approaching the point where I will buy one of these two units. Could you also give us some impressions on the size of the two units. From the pictures, it seems that the waveterminal might be smaller. Since I like to throw my audio gear in my computer bag when I travel and when I go to and from my office, portability is a nice bonus.

Thanks again for your insights.
I have a friend who switched from the Transit to a Waveterminal. He is using a powerbook and a MSB DAC. playing Apple Lossless files.

After switching to the Waveterminal he said "So that's what the music is supposed to sound like, it's like unfogging your glasses."

He also said he liked the way music sounded with the Transit, but he really likes how it sounds now.

Ed
One thing about the Transit - I use it with Foobar player and ASIO plug-in. These are critical on a PC to get the quality out of it. I also playback exclusively with 24/96 through my DAC. This makes all the difference. Leaves all transports in the dust.

I am thinking hard about buying an Airport Express and modding it to have a S/PDIF coax out. This might be the best solution for iMac, although I prefer a wired USB connection.
Bought an AirPort Express and I will be modding it soon... I will let you all know if it is as good as the Transit on a PC.